Functionally different GPI proteins are organized in different domains on the neuronal surface

Abstract

We have investigated the organization, on the plasma membrane and in detergent-insoluble membrane vesicles, of two neuronal glycosylphosphatidylinositolanchored (GPI) proteins: Thy-1, a negative regulator of transmembrane signalling; and prion protein, whose rapid endocytosis and Cu 2ϩ binding suggest that it functions in metal ion uptake. Prion protein occurred on the neuronal surface at high density in domains, located primarily at the cell body, which were relatively soluble in detergent. Thy-1, although much more abundantly expressed on neurons, occurred at lower density over much of the surface of neurites (and in lower abundance at the cell body) in domains that were highly resistant to detergent solubilization. Detergentinsoluble membrane vesicles contained Thy-1 at a density similar to that on the neuronal surface. Vesicles containing each protein could be separated by immunoaffinity isolation; lectin binding showed that they were enriched in different glycoproteins. Our results demonstrate a structural diversity of the domains occupied by functionally different GPI proteins.

TRAF interactions with raft‐like buoyant complexes, better than TRAF rates of degradation, differentiate signaling by CD40 and EBV latent membrane protein 1

“…In contrast, TRAF3-clusters of gold particles were close to the plasma membrane and were reminiscent of some previously published electron-micrographies of membrane microdomains. 41,42 Signaling by receptors (and pseudoreceptors) of the TNF-receptor family involve multiple partners, pathways and regulatory mechanisms. Many aspects of these mechanisms are highly variable depending on the host cell (for example, see reference 43).…”

Rafts in oligodendrocytes: Evidence and structure–function relationship

“…These findings would favor the notion (Brügger et al, 2004;Madore et al, 1999) that the disparate results obtained by different detergents may relate to the co-existence of different domains, characterized by differences in composition. However, claims have been made that differential insolubility of proteins in different detergents is not sufficient to imply their association with distinct lipid rafts (Chamberlain, 2004;Pike, 2004).…”

Raft-mediated Trafficking of Apical Resident Proteins Occurs in Both Direct and Transcytotic Pathways in Polarized Hepatic Cells: Role of Distinct Lipid Microdomains

“…Moreover, in the indirect pathway, LubWX microdomains localized GPI-GFP becomes more soluble after cholesterol depletion without affecting its apical targeting, whereas at the same conditions the LubWX insolubility of MDR1-GFP is not affected. Accordingly, these data may suggest a structural diversity of both LubWXresistant domains, which may rely, for example, on differences in lipid ordering that would affect detergent accessibility and hence, detergent solubility (Madore et al, 1999). Indeed, one could readily envision that a relatively less ordered raft domain could more easily accommodate the helical domains of multispanning membrane proteins.…”